Rotorcrafts with multi-blade rotor hub configurations often include a main rotor assembly for supplying forces for flight, and a tail rotor assembly (sometimes referred to as an anti-torque system) that stabilizes and influences the flight direction of the rotorcraft. The rotor blades (sometimes called tail rotors) in the tail rotor assembly are subject to internal and external disturbances affecting maneuverability of the rotorcraft. One example of an external disturbance is wind that can create undesirable vibrations in the tail rotor assembly transmitted to the body of the rotorcraft. An example of an internal disturbance is oscillations of the tail rotor blades relative to each other and the drive shaft. The oscillations may be caused by lead-lag movement of the blades or scissor-mode motions between blades of different blade pairs and rotation of the drive shaft.
Effects of these disturbances are more pronounced in rotorcraft due to radial air flow to the blades, as opposed to fixed wing aircraft propellers. Failure to treat or mitigate the effect of these disturbances increases mechanical stress resulting in fatigue of the tail rotor blades and other rotorcraft components. Catastrophic results can also occur in a “ground resonance” phenomenon when untreated oscillating frequency matches a resonant frequency of the rotorcraft. One way to treat or mitigate the effect involves using dampers to reduce the frequency or amplitude of unwanted vibrations to counter oscillations in the rotor blade assembly.